Breech loaded syringe and method of breech loading same

ABSTRACT

A syringe wherein a piston is moved axially through a tubular barrel to deliver liquid medicament and the like outwardly through a needle connected through an inner end of the barrel. A control is provided for selectively deforming the piston to permit the barrel to be preloaded with the liquid medicament through the breech end thereof with the piston being brought into engagement with the liquid while a fluid bypass passage is provided around the piston to the breech end of the barrel, thereby to vent air outwardly from the space between the piston and the liquid medicament during the insertion of the piston.

United States Patent Stumpf et al.

[54] BREECH LOADED SYRINGE AND METHOD OF BREECH LOADING SAME [72]Inventors: Marvin D. Stumpl, 9301 Clarion Drive, St. Louis, Mo. 63136;Elmer A. Koenig, 1702 Ben Davis Lane, Kirkwood, Mo. 63122 [22] Filed:Sept. 23, 1969 [21] Appl. No.: 860,223

[52] US. Cl. ..12s/21s P, 53/57 [51] Int. Cl. ..A6lm 5/00 [58] Field ofSearch ..128/218 R, 218 P, 218 M, 220; 53/57 [56] References Cited 7UNITED STATES PATENTS 3,391,518 7/1968 Gettig et al. ..53/37 X 3,470,67110/1969 Gettig et al 841,701 l/l907 DeLisle 1,139,368 5/1915 Pierce..128/218 P [451 Dec. 12, 1972 l-lein ..128/218 R Brown ..128/218 R UXVan Sickle ..128/218 P UX Ogle ..128/218 P X Von Pechmann ..128/218 RPrimary Examiner-Joseph S. Reich Attorney-Donald S. Olexa, Jerome M.Teplitz and John G. Heimovics A syringe wherein a piston is movedaxially through a tubular barrel to deliver liquid medicament and thelike outwardly through a needle connected through an inner end of thebarrel. A control is provided for selectively deforming the piston topermit the barrel to be preloaded with the liquid medicament through thebreech end thereof with the piston being brought into engagement withthe liquid while a fluid bypass passage is provided around the piston tothe breech end of the barrel, thereby to vent air outwardly from thespace between the piston and the liquid medicament during the insertionof the piston.

ABSTRACT 8 Claims, 9 Drawing Figures I PATENTEDDECIZIHR 3.705 582 SHEET2 HP 2 I Jig- J? BREECH LOADED SYRINGE AND METHOD OF BREECII LOADINGSAME BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to syringes and in particular to piston-type syringes.

2. Description of the Prior Art In the conventional piston syringe, thefilling of the syringe is effected through the needle connecting end.Such a method of filling the syringe is undesirable where the filledsyringe is to be stored, such as where the syringe comprises a prefilledsyringe. Further, such needle end filling is inimical to good aseptictechniques. Illustratively, it has been found that the narrow lumens ofthe needle or needle connector tip become clogged by the driedmedicament.

One attempted method of resolving this problem has been to load thesyringe through the breech end of the barrel. Such a loading of thesyringe provides improved storage characteristics where air is removedfrom between the piston and liquid medicament upon insertion of thepiston. Thus, in the prior art devices for providing such breechloading, needles, rods, valves, conical shaped sleeves, etc. have beenemployed to permit venting of the trapped air. Not only are such meansrelatively expensive, but also, such means have been found to lead tocontamination of the liquid medicament.

SUMMARY OF THE INVENTION The present invention comprehends an improvedsyringe structure wherein the piston, during insertion through thebreech end of the barrel into engagement with the previously depositedliquid medicament, is deformed so as to provide a bypass vent. Thedeforming means may comprise a tubular element adapted to receive thepiston under compression and having a clearance with the barrelpermitting movement of the inner end of the element through the breechend of the barrel into juxtaposition with the liquid medicament whereinthe trapped air is vented through the clearance space between the sleeveand the barrel. Upon reaching the fully inserted position, the piston isremoved from its position within the sleeve end thereby permitting the,piston to expand into sealed sliding engagement with the barrel wall.The piston may be carried on the inner end of a shaft extending from thepiston to outwardly of the barrel outer end.

In one specific embodiment of the invention, the shaft extends coaxiallythrough a tubular sleeve having a bore radially enlarged at its innerend to define a piston receiving recess. The tubular sleeve also has arecess at its outer end for receiving in nested relationship the thumbpiece of the shaft. Movement between the shaft and the sleeve may beeffected manually to provide the selective deformation and release ofthe piston.

Alternatively, the piston may be deformed by a rib element on the innerend of the sleeve which extends the length of the piston to deform anouter wall portion thereof radially inwardly and thereby form a fluidbypass passage permitting the air to be vented from the barrel duringthe insertion of the piston. If desired, a plurality of such ribelements may be provided to form a plurality of such bypass passages forventing during the piston insertion step.

Iii!

' air from the barrel as the piston is moved to the liquid medicament,and discontinuing the deforming of the piston upon the piston reachingthe liquid medicament to cause the piston to have sealed slidingengagement with the barrel. The filling of the syringe may be effectedto provide a prefilled syringe unit which may be stored for subsequentuse as desired. In such case, the needle end of the syringe ismaintained sealingly closed. Alternatively, the syringe will be breechfilled at the time of use by the above indicated steps.

BRIEF DESCRIPTION OF THE DRAWING Other features and advantages of theinvention will be apparent from the following description taken inconnection with the accompanying drawing wherein:

FIG. 1 is a fragmentary enlarged front view of a syringe embodying theinvention with portions broken away to illustrate the invention;

FIG. 2 is a view similar to that of FIG. 1 but illustrating thearrangement of the syringe during the piston inserting operation;

FIG. 3 is an exploded view with portions broken away illustrating thearrangement of the piston and sleeve assembly prior to insertion intothe syringe barrel;

FIG. 4 is a front view of one form of sleeve thereof;

FIG. 5 is a fragmentary bottom end view thereof;

FIG. 6 is a front view of the sleeve used in the syringe shown in FIGS.1-3, with a portion broken away to pro vide a clear illustration of theinvention;

FIG. 7. is a bottom end view of the sleeve of FIG. 6;

FIG. 8 is a front view of still another modified form of sleeve thereofwith a portion broken away to illus trate the invention; and

FIG. 9 is a bottom end view of the sleeve of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the exemplary embodiment ofthe invention as disclosed in FIGS. l-3 of the drawing, a syringegenerally designated 10 is shown as having a conventional tubular barrel1 l defining a chamber l2v opening axially outwardly through an outerend 13. The inner end 14 of the barrel 1] is provided with an outlet 15opening into a connector 16 for attaching a needle, such as conventionalneedle 17, in fluid transfer association with the inner end of thebarrel. In the illustrated embodiment, the connector comprises aconventional luer lock connector, it being understood that any suitableneedle connecting means may be utilized. Prior to the installation ofthe needle 17 onto the connector 16, connector 16 may be conventionallyclosed by a conventional cap 18, as shown in FIGS. 2 and 3.

The syringe 10 may comprise a prefilled syringe wherein a body ofliquid, such as liquid medicament 19, is provided in the portion 20 ofthe chamber 12 inwardly of a piston 21. In the illustrated embodiment,the liquid 19 is delivered into the chamber 12 through the outer end 13in a breech loading operation. The

Inuun npiston 21 is then brought into the chamber 12 through the outerend 13 to engage the liquid 19 as shown in FIG. 2. To permit suchinsertion of the piston, a bypass passage 22 is provided around thepiston from the inner chamber portion 20 to the outer opening 13 wherebyair may be vented from the chamber 12 as the piston is moved downwardlytherethrough to the position of FIG. 2.

The invention comprehends the provision of the vent passage 22 by meansof a tubular element, or sleeve, 23 having an outside diameter slightlysmaller than the inside diameter of the barrel 11. The bore 24 of sleeve23 is stepped at 25 to define a radially enlarged inner end bore portion26 adapted to receive the piston 21 as shown in FIG. 2. Piston 21 ispreferably formed of a resilient material, such as neoprene rubber, topermit the ready compression thereof into the bore portion 26 of thesleeve 23 as by urging the sleeve axially forward relative to the piston21 until the piston is encased in portion 26 as shown in FIG. 3. Thepiston is secured to an end connector portion 27 of a shaft 28 having anouter thumb piece 29. Shaft 28 extends coaxially through the bore 24 ofsleeve 23. As shown in FIG. 2, shaft 28 is somewhat smaller intransverse dimension than the diameter of bore 24, permitting the readyaxial movement of the shaft 28 therethrough when desired. To providerelative movement between the shaft 28 and sleeve 23 and to provide forthe movement of the sleeve 23 into the barrel 11, the outer end of thesleeve is provided with a flange 30. Flange 30 is spaced outwardly ofthe conventional outturned flange 31 of the barrel to permit the user toinsert his fingers under flange 30 with his thumb on thumb piece 29 andthereby readily effect a movement of the piston 21 inwardly from the endportion 26 when desired. Thus by maintaining the piston 21 in contactwith the liquid medicament 19 and urging the sleeve 23 outwardly, thelower end of the sleeve is withdrawn from the piston permitting thepiston to expand radially into sliding sealing engagement with thebarrel wall in bore portion 20' thereby to permit subsequent controlleddelivery of the liquid medicament outwardly through needle 17 asdesired.

The flange 30 of the sleeve 23 has a recess formed in the upper surface32 which recess 35 is of a size and shape to receive in nestedrelationship the thumb piece 29 of the shaft 28 when the shaft is fullydepressed relative to the sleeve 23. In moving the shaft 28 relative tothe sleeve 23 from the position of FIG. 2 to the position of FIG. 1, thethumb piece 29 will nest in the recess 35 and create the appearance of aone piece plunger unit.

In the normal use, the piston 21 may be provided retracted within boreportion 26 as shown in FIG. 3, permitting the movement of the assembledpiston and sleeve 23 into the barrel 11 as discussed above. However,alternatively, the piston may be mounted on the shaft end 27 inwardly ofthe sleeve (in the arrangement seen in FIG. 1) and inserted into theopen end 13 of the barrel 11. The piston is then caused to move into thebore portion 26 by a combination of forces directed by the users fingerson the outer surface 32 of the flange 30 and the fluid pressure withinthe bore 12 ahead of the piston 21 thereby to cause the piston to moveaxially into the sleeve bore end 2 6. Once the piston is fully receivedin bore end 26, further movement of the assembly may be effected asdiscussed above as the sleeve and piston structure are now disposed inthe arrangement shown in FIG. 2. This method of bringing the piston intothe bore end 26 at the time of assembly is advantageous where the piston21 is formed of a material which may take a permanent set if storedwithin the sleeve bore 24 for a protracted period of time. The piston21, sleeve 23, and shaft 28 may, of course, be assembled together byinserting the shaft 28 through the sleeve 23, and then mounting thepiston 21 onto the inner end 27 of the shaft so that these parts occupythe relative positions shown in FIG. 1. The piston is deformed toprovide a vent passage around the piston 21 by effecting relativemovement between the shaft with the piston connected thereto, and thesleeve. In the illustrated embodiment of FIGS. 1-3, such relativemovement positions the piston 21 in the sleeve bore end 26 and thiseffects deformation of the piston by urging peripheral portions thereofradially inwardly, the piston being retained in the bore end 26 by theinherent resiliency thereof.

Thus, the syringe 10 provides an improved structure permittingprefilling of the syringe in an aseptic manner by a breech loading ofthe liquid medicament therein. As indicated above, the liquid medicamentmay be retained in the prefilled syringe by the subsequent installationof the piston 21 as discussed above, whereby the piston may be broughtinto engagement with the upper surface of the liquid by a ventedmovement of the piston through the barrel, thereby maintaining theaseptic condition of the breech loaded syringe. When the syringe is tobe used, the cap 18 is removed and the needle 17 installed on theconnector 16 in the conventional manner whereupon the liquid medicamentmay be delivered through the needle by suitable manipulation of theshaft 28 by the users fingers engaging flange 31 and thumb piece 29.

The invention comprehends broadly providing a means for deforming thepiston 21 during its insertion through the bore 12 to define a bypasspassage 22 whereby the bore '12 is vented to facilitate the movement ofthe piston fully to the position of FIG. 2. As discussed above, in oneform, the means for forming the bypass passage 22 may comprise means forreceiving the piston under compression within one end of the tubularsleeve 23. The sleeve construction is illustrated in FIGS. 6 and 7. Aswill be obvious to those skilled in the art, other forms of pistondeforming means may be provided within the scope of the invention.Illustratively, in FIG. 4, a sleeve 123 is shown to comprise a sleevesimilar to sleeve 23 but having a plurality of circumferentially spacedend prongs 133 which effectively distort the piston when the piston isretracted into the space 126 radially within the prongs. In theillustrative embodiment of FIG. 4, three such prongs are provided spacedabout the axis of the sleeve. In FIGS. 8 and 9, a further modified formof sleeve 223 is shown to comprise a sleeve having a depending prong 223provided with a radially inwardly projecting rib 234 which effectivelydistorts the piston to define an air bypass vent passage for venting thebarrel during the installation of the piston.

Each of the sleeves 23, 123, and 223 is similar to the others andfunctions in a similar manner except as otherwise noted. In eachembodiment, means are provided for deforming the piston during insertionthereof into the barrel bore to define a vent passage. The deformingmeans are carried on an elongated element which extends to outwardly ofthe barrel serving as a means for effecting a separation of thedeforming 'means from the piston after the piston reaches the desiredfully inserted position whereby the piston may then function in thenormal manner within the barrel. As will be obvious to those skilled inthe art, the element carrying the deforming means may have otherconfigurations in addition to the tubular sleeve configuration of theillustrative embodiments. The different parts of these syringes may bemade of suitable materials, such as plastics, permitting relative easeof sterilization. Thus, the syringes may comprise one-time use,prefilled syringes.

The foregoing disclosure of specific embodiments is illustrative of thebroad inventive concepts comprehended by the invention.

I claim: 1. In a syringe having a tubular barrel defining a chamberopening axially through the outer end of the barrel, and a needleconnecting portion at the inner end of the barrel for connecting aneedle in fluid flow association with said chamber, the improvementcomprising:

a resilient piston arranged to have sealing sliding engagement with thebarrel in said chamber; first means secured to said piston and extendingfrom said piston to outwardly of said outer end for moving said pistoninto said chamber through said outer end during insertion thereof insaid barrel and for moving said piston to discharge fluid from saidchamber in response to a manually applied force on said first meansduring operational use of the syringe; and second means carried by saidfirst means and extending from within said chamber to outwardly of saidouter end, said second means being movable in one direction relative tosaid first means to deform said piston for forming fluid bypass meansaround said piston for venting the chamber portion forward of saidpiston, and movable in the direction opposite said one directionrelative to said first means for removing the fluid bypass means wherebythe piston sealingly engages with the barrel to force fluid from saidchamber through said needle connecting portion as an incident ofmovement of said piston in said chamber toward said inner end inresponse to said applied force on said first means.

2. in a syringe having a tubular barrel defining a chamber openingaxially through the outer end of the barrel, and a needle connectingportion at the inner end of the barrel for connecting a needle in fluidflow association with said chamber, the improvement comprising:

a resilient piston arranged to have sealing sliding engagement with thebarrel in said chamber;

first means secured to and extending from said piston to outwardly ofsaid outer end for manipulating said piston during operational use ofthe syringe; and

second means carried by said first means, said first and second meansbeing relatively movable a. for forming fluid bypass means around saidpiston for venting the chamber portion forward of said piston, and

b. for removing the fluid bypass means whereby the piston is in sealingengagement with the barrel to force fluid from said chamber through saidneedle connecting portion. as an incident of movement of said piston insaid chamber toward said inner end, said second means comprising meanshaving a tubular inner end removably receiving said piston, and meansfor causing axial removal of said piston from said tubular inner end,said second means having a clearance with said barrel defining saidfluid bypass means to said outer end of the barrel, said second meansalso having an axially inner end for retaining the piston axiallyinwardly of said tubular end subsequent to said removal.

3. In a syringe having a tubular barrel defining a chamber openingaxially through the outer end of the barrel, and a needle connectingportion at the inner end of the barrel for connecting a needle in fluidflow association with said chamber, the improvement comprising:

a resilient piston arranged to have sealing sliding engagement with thebarrel in said chamber;

first means secured to and extending from said piston to outwardly ofsaid outer end for manipulating said piston during operational use ofthe syringe; and

second means carried by said first means and extending from within saidchamber to outwardly of said outer end, said first and second meansbeing selectively relatively movable.

a. for forming fluid bypass means around said piston for venting thechamber portion forward of said piston, and

b. for removing the fluid bypass means whereby the piston is in sealingengagement with the barrel to force fluid from said chamber through saidneedle connecting portion as an incident of movement of said piston insaid chamber toward said inner end in response to an applied force onsaid first means, said second means comprising means removably extendingthe length of said piston between said piston and said barrel fordeforming said piston to form a plurality of fluid bypass passagesbetween the deformed piston and the barrel which communicate with saidouter end of the barrel, said passages defining said fluid bypass means,said second means comprising a plurality of angularly spaced elementsproviding said fluid bypass means.

4. In a syringe having a tubular barrel defining a chamber openingaxially through the outer end of the barrel, and a needle connectingportion at the inner end of the barrel for connecting a needle in fluidflow association with said chamber, the improvement comprising:

a resilient piston arranged to have sealing sliding engagement with thebarrel in said chamber;

first means extending from said piston to outwardly of said outer endfor manipulating said piston during operational use of the syringe; and

second means carried by said first means and extending from within saidchamber to outwardly of said outer end, said first and second meansbeing selectively relatively movable a. for forming fluid bypass meansaround said piston for venting the chamber portion forward of saidpiston, and b. for removing the fluid bypass means whereby the piston isin sealing engagement with the barrel to force fluid from said chamberthrough said needle connecting portion as an incident of movement ofsaid piston in said chamber toward said inner end, said second meanscomprising a tubular element having an axial bore provided with aportion at the inner end of said tubular element of greater diameterthan other portions of said bore for receiving said piston, said tubularelement removably extending the length of said piston between the pistonand said barrel for deforming the piston to define said fluid bypassmeans between the deformed piston and the barrel which communicate withsaid outer end of the barrel. 5. The method of filling a syringe havinga barrel with a bore open at the breech end of the barrel for receivinga liquid medicament during the filling of the syringe, and a shaft andpiston assembly comprising a resilient piston for sliding sealingengagement with the barrel in the bore, and a shaft connected to thepiston and responsive to an applied force thereon for moving the pistontoward the inner end of the barrel to discharge the medicament from thebore during operational use of the syringe comprising the steps of:

providing said shaft and piston assembly with a relatively movableelongate member adapted to deform said piston upon movement thereof inone "Ill direction relative to said shaft; moving said elongate memberin said one direction relative to said shaft to deform said piston;

inserting said piston and shaft assembly and said elongate member intothe bore through the breech end thereof;

moving the shaft and piston assembly and elongate member toward theinner end of the barrel with said piston deformed to provide fluidbypass means within the barrel from a point ahead of said piston to saidbreech end for venting air from the barrel as said piston is movedtoward the liquid medicament; and moving said elongate member in thedirection opposite said one direction relative to said shaft to causesaid piston to have scaled sliding engagement with the barrel.

6. The method of filling a syringe with liquid medicament of claim 5wherein substantially the entire piston is deformed away from contactwith the barrel during the step of moving the shaft and piston assemblyand the elongate member toward the inner end of the barrel.

7. The method of filling a syringe with liquid medicament of claim 5wherein only a portion of the piston is deformed away from contact withthe barrel during the step of moving the shaft and piston assembly andthe elongate member toward the inner end of the barrel.

8. The method of filling a syringe with liquid medicament of claim 5wherein the step of movin said second means in said one directionrelative to san first means to deform said piston is performed prior tothe step of inserting said shaft and piston assembly into the breech endof the barrel, and said piston is maintained deformed by said elongatemember until it is substantially moved to the liquid medicament.

1. In a syringe having a tubular barrel defining a chamber openingaxially through the outer end of the barrel, and a needle connectingportion at the inner end of the barrel for connecting a needle in fluidflow association with said chamber, the improvemEnt comprising: aresilient piston arranged to have sealing sliding engagement with thebarrel in said chamber; first means secured to said piston and extendingfrom said piston to outwardly of said outer end for moving said pistoninto said chamber through said outer end during insertion thereof insaid barrel and for moving said piston to discharge fluid from saidchamber in response to a manually applied force on said first meansduring operational use of the syringe; and second means carried by saidfirst means and extending from within said chamber to outwardly of saidouter end, said second means being movable in one direction relative tosaid first means to deform said piston for forming fluid bypass meansaround said piston for venting the chamber portion forward of saidpiston, and movable in the direction opposite said one directionrelative to said first means for removing the fluid bypass means wherebythe piston sealingly engages with the barrel to force fluid from saidchamber through said needle connecting portion as an incident ofmovement of said piston in said chamber toward said inner end inresponse to said applied force on said first means.
 2. In a syringehaving a tubular barrel defining a chamber opening axially through theouter end of the barrel, and a needle connecting portion at the innerend of the barrel for connecting a needle in fluid flow association withsaid chamber, the improvement comprising: a resilient piston arranged tohave sealing sliding engagement with the barrel in said chamber; firstmeans secured to and extending from said piston to outwardly of saidouter end for manipulating said piston during operational use of thesyringe; and second means carried by said first means, said first andsecond means being relatively movable a. for forming fluid bypass meansaround said piston for venting the chamber portion forward of saidpiston, and b. for removing the fluid bypass means whereby the piston isin sealing engagement with the barrel to force fluid from said chamberthrough said needle connecting portion as an incident of movement ofsaid piston in said chamber toward said inner end, said second meanscomprising means having a tubular inner end removably receiving saidpiston, and means for causing axial removal of said piston from saidtubular inner end, said second means having a clearance with said barreldefining said fluid bypass means to said outer end of the barrel, saidsecond means also having an axially inner end for retaining the pistonaxially inwardly of said tubular end subsequent to said removal.
 3. In asyringe having a tubular barrel defining a chamber opening axiallythrough the outer end of the barrel, and a needle connecting portion atthe inner end of the barrel for connecting a needle in fluid flowassociation with said chamber, the improvement comprising: a resilientpiston arranged to have sealing sliding engagement with the barrel insaid chamber; first means secured to and extending from said piston tooutwardly of said outer end for manipulating said piston duringoperational use of the syringe; and second means carried by said firstmeans and extending from within said chamber to outwardly of said outerend, said first and second means being selectively relatively movable.a. for forming fluid bypass means around said piston for venting thechamber portion forward of said piston, and b. for removing the fluidbypass means whereby the piston is in sealing engagement with the barrelto force fluid from said chamber through said needle connecting portionas an incident of movement of said piston in said chamber toward saidinner end in response to an applied force on said first means, saidsecond means comprising means removably extending the length of saidpiston between said piston and said barrel for deforming said piston toform a plurality of fluid bypass passages between the deformed pistonand the barrel which communicate with said outer end of the barrel, saidpassages defining said fluid bypass means, said second means comprisinga plurality of angularly spaced elements providing said fluid bypassmeans.
 4. In a syringe having a tubular barrel defining a chamberopening axially through the outer end of the barrel, and a needleconnecting portion at the inner end of the barrel for connecting aneedle in fluid flow association with said chamber, the improvementcomprising: a resilient piston arranged to have sealing slidingengagement with the barrel in said chamber; first means extending fromsaid piston to outwardly of said outer end for manipulating said pistonduring operational use of the syringe; and second means carried by saidfirst means and extending from within said chamber to outwardly of saidouter end, said first and second means being selectively relativelymovable a. for forming fluid bypass means around said piston for ventingthe chamber portion forward of said piston, and b. for removing thefluid bypass means whereby the piston is in sealing engagement with thebarrel to force fluid from said chamber through said needle connectingportion as an incident of movement of said piston in said chamber towardsaid inner end, said second means comprising a tubular element having anaxial bore provided with a portion at the inner end of said tubularelement of greater diameter than other portions of said bore forreceiving said piston, said tubular element removably extending thelength of said piston between the piston and said barrel for deformingthe piston to define said fluid bypass means between the deformed pistonand the barrel which communicate with said outer end of the barrel. 5.The method of filling a syringe having a barrel with a bore open at thebreech end of the barrel for receiving a liquid medicament during thefilling of the syringe, and a shaft and piston assembly comprising aresilient piston for sliding sealing engagement with the barrel in thebore, and a shaft connected to the piston and responsive to an appliedforce thereon for moving the piston toward the inner end of the barrelto discharge the medicament from the bore during operational use of thesyringe comprising the steps of: providing said shaft and pistonassembly with a relatively movable elongate member adapted to deformsaid piston upon movement thereof in one direction relative to saidshaft; moving said elongate member in said one direction relative tosaid shaft to deform said piston; inserting said piston and shaftassembly and said elongate member into the bore through the breech endthereof; moving the shaft and piston assembly and elongate member towardthe inner end of the barrel with said piston deformed to provide fluidbypass means within the barrel from a point ahead of said piston to saidbreech end for venting air from the barrel as said piston is movedtoward the liquid medicament; and moving said elongate member in thedirection opposite said one direction relative to said shaft to causesaid piston to have sealed sliding engagement with the barrel.
 6. Themethod of filling a syringe with liquid medicament of claim 5 whereinsubstantially the entire piston is deformed away from contact with thebarrel during the step of moving the shaft and piston assembly and theelongate member toward the inner end of the barrel.
 7. The method offilling a syringe with liquid medicament of claim 5 wherein only aportion of the piston is deformed away from contact with the barrelduring the step of moving the shaft and piston assembly and the elongatemember toward the inner end of the barrel.
 8. The method of filling asyringe with liquid medicament of claim 5 wherein the step of movingsaid second means in said one direction relative to said first means todeform said piston is performed prior to the step of inserting saidshaft and piston assembly into the breech end of the barrel, and saidpiston is maintained deformed by said elongate member until it Issubstantially moved to the liquid medicament.